IDENTIFICATION, CHARACTERIZATION, AND DEVELOPMENTAL REGULATION OF A RECEPTOR GUANYLYL CYCLASE EXPRESSED DURING EARLY STAGES OF DROSOPHILA DEVELOPMENT

Membrane forms of guanylyl cyclase are single-transmembrane proteins t hat are activated by the binding of specific peptide ligands to their extracellular domains. In this report, we describe the identification and characterization of a Drosophila cDNA clone encoding a protein, Dr GC-1, with high sequence identity to members of this family of recepto r proteins, The protein contains a single, hydrophobic domain predicte d to represent a transmembrane segment separating an extracellular dom ain with significant sequence identity (30%) to sea urchin egg peptide receptors from intracellular domains containing a protein kinase-like domain followed by a region with high sequence identity (65%) to cycl ase catalytic domains found in receptor guanylyl cyclases from both ve rtebrates and invertebrates. In contrast to other members of this fami ly, DrGC-1 is predicted to contain a carboxyl-terminal extension of 43 0 residues that has no homology to any described protein. Northern ana lysis indicates that DrGC-1 transcripts are present at variable levels in all stages of development. In situ hybridization demonstrates that high levels of uniformly distributed transcript are present in 0-2-h embryos. Later in embryogenesis (14-18 h), elevated levels of hybridiz ation appear to be preferentially associated with muscle fibers.